Earlier this month, a visitor to the National Gallery in London slashed a Thomas Gainsborough painting. (It went back on view yesterday.) Noah Charney has a suggestion:

"There is no such thing as a risk-free museum, but there is a way to minimize risk of damage and theft, a way that many top museums have chosen (the Louvre, the Prado, the Van Gogh, the Uffizi, to name a few), but which the National Gallery has not — install airport-style security at the entrance. It is a modest inconvenience to museum-goers, but one that they will be used to, from travel in this day and age: moving single-file through a metal detector and having their bags scanned before entering the museum to explore freely. This method would prevent attacks with metal objects, like knives and screwdrivers, and would be a strong deterrent to any attacks at all — potential perpetrators are likely to be scared off by having to pass under the scrutiny of security and move slowly into the museum, clearly filmed on CCTV, and with nervous or suspicious behavior likely to be noted before they even enter. In an era of concern over terrorist attacks on populous sites, this is also a good idea. Of course, a determined baddie can still find ways to damage art, but the risk is mitigated."